I just bought a new OEM style one and cut holes for 6x9's and covered it with black vinyl from a hobby store. It matches my interior very well. I did this over 10 years ago and it still looks great. They now sell ones like I made for 40 bucks. They make them with speaker cutouts as well. I don't like the fiberglass look its too modern looking.

http://www.mustangsunlimited.com/ite...p?T1=PT1958+01

http://www.mustangsunlimited.com/ite...p?T1=PT2958+01

 

i wrapped the masonite (i think that's what it's called) with the grill material. the 6x9's mounted in the factory holes (not in the pkg tray). i don't have any pics of it, it was about 10 yrs ago. my friend has the car now, it still looks good. just make sure you spray the wood flat black so when the grill material is stretched over, it doesn't show any brown

 

Well I lucked out and my work was giving away 4x8 sheets of textured kydex, they are even white already! Free is good. Thanks to everyone for all of their suggestions.